fans

Question 1

3 types of pressure from fans

Answer 1

static
velocity
total pressure

Question 2

airflow through the system is controlled by this

Answer 2

damper

Question 3

type of pressure that air exerts on the inside of duct walls

Answer 3

static

Question 4

type of pressure measured at fan discharge with ducting 90 degrees

Answer 4

static

Question 5

type of pressure caused by air flowing through a duct and is felt only by the surfaces that the air actually strikes

Answer 5

velocity

Question 6

type of pressure measured by connecting one end of the manometer at right angles to the duct wall and the other end with the opening facing the airflow

Answer 6

velocity

Question 7

pressure conversion static to velocity

Answer 7

decreasing cross sectional area

converging

Question 8

pressure conversion velocity to static

Answer 8

increasing cross sectional area

diverging

Question 9

mechanical draft type where pressure in the furnace is below atmospheric pressure.
Fan located between the boiler and the chimney

Answer 9

induced draft

Question 10

centrifugal blade fan most effecient and require less horsepower

Answer 10

backward incline blade fan

Question 11

centrifugal blade fan has a lower speed for the same volume, low speed good for hvac application

Answer 11

forward blade fan

Question 12

centrifugal blade fan are used where high speed requires a stronger wheel

Answer 12

radial blade fan

Question 13

centrifugal fan casing cause this pressure change

Answer 13

velocity of static

Question 14

advantage of axial flow fans

Answer 14

low cost

compactness

Question 15

axial fans should not be used in these system

Answer 15

ducted air distribution system

Question 16

centrifugal or axial fans rotate at higher rpm for same air flow

Answer 16

axial

Question 17

tube axial or vane axial has less airflow swirl

Answer 17

vane axial

Question 18

another name for impellers on centrifugal fans

Answer 18

wheels

Question 19

used on fans with constant speed motors and are the least expensive efficient control

Answer 19

outlet damper control

Question 20

radial vanes installed on fan inlet. vane shaft interconnect so that all the vanes rotate open and closed in unison

Answer 20

variable inlet vane control

Question 21

used on many centrifugal fans to muffle the loud inlet sound generated by the increased air velocity and air shock as it flows into the eye of the fan wheel

Answer 21

air inlet silencer

Question 22

isolator absorb vibration and allow for large thermal movement

Answer 22

spring type

Question 23

isolator more compact, less flexible and become hardened with age

Answer 23

rubber disk

Question 24

isolator have large capacity to absorb vibration

Answer 24

oil type vibration

Question 25

ground brush arrangement mounted on isolated fans to ground the static electricity generated while the fan is running

Answer 25

static arrest

Question 26

cooling tower fan blade tip to housing ring clearance

Answer 26

1/2% of fan diameter